1. Field of the Invention
The present invention is related to a contact structure, a connecting structure thereof and a method of forming the same. In particular, the present invention is related to a contact structure, a method of forming the same and a connecting structure thereof, where a bonding material is easily penetrated through and stress concentration does not occur during bonding process.
2. Description of Related Art
As technology advances, all kinds of electronic devices are developed towards miniaturization and multiple functions. Hence, in order for chips in electronic device to be able to transmit or receive more signals, contacts electrically connected between chips and circuit boards are also developed towards high density.
In the prior art, a chip and a glass substrate are electrically connected mostly by disposing an anisotropic conductive film (ACF) between contacts of the chip and conductive structures of the glass substrate. The contacts of the chip and the conductive structures of the glass substrate both face the ACF. Afterwards, the contact of the chip, the ACF and the conductive structure of the glass substrate are laminated so that each of the contacts of the chip is electrically connected to the conductive structure corresponding to the contact on the glass substrate through conductive particles in the ACF.
However, as a density of the contacts on the chip and a density of the conductive structures of the glass substrate increase, a space between the contacts on the chip and a space between the conductive structures are both reduced. Therefore, it is likely that the contacts on the chip may be electrically connected with adjacent contacts or conductive structures through the conductive particles in the ACF, which in turn results in short circuit or electric leakage.
In view of the foregoing, a pillar-shaped polymer bump covered with a metal layer on its surface has been proposed as a contact structure of a chip. Further, a proposed method of electrically connecting the contact on the chip with the conductive structure of the glass substrate includes first disposing a non-conductive viscose layer between the chip and the conductive structure of the glass substrate. Thereafter, the chip is laminated on the glass substrate so that the pillar-shaped polymer bump penetrates through the non-conductive viscose, contacts the conductive structure of the glass substrate and electrically connects therewith.
However, the issue of stress concentration is prone to occur when the pillar-shaped polymer bump is laminated, which tends to make the metal layer crack and reduce the electrical reliability thereof.